Originally Posted by KenM
Yes thanks all, a very odd looking Swift, it’s the white forked tail with the black centre spine that looks to my eye at least quite unusual.
Well not an ‘odd looking Swift’ as such, but an odd looking photo
of a Swift -
in addition to what others have said about the natural phenomena of light on black plumage, I think a certain amount of overexposure when taking a shot (ie where light strongly hits one surface more than the rest of the frame) can also burn out subtle colour and detail so can produce odd artefacts in a photo.
It is interesting (and a cautionary tale for ID purposes!)